This invention relates to a suspension cell culture system and apparatus therefor. More particularly, this invention relates to an agitated suspension cell culture system and agitator apparatus therefor.
In recent years there has been rapid growth in the development of various methods for the culturing of cells in suspension. The attainment of high cell densities is a primary objective of many of these approaches. The use of a cell culture vessel with controlled agitation by means of a magnetic stirrer bar or a mechanically driven impeller on a shaft is a typical feature of these methods. Examples of such apparatus are disclosed in U.S. Pat. Nos. 2,958,517; 3,039,932; 3,572,651; 3,622,122; and 3,649,465. These are essentially batch type spin culture devices or spinner flasks in which the cells are incubated in a fixed amount of nutrient under appropriate culture conditions until cell growth has ceased.
Continuous cell culture systems and apparatus also have been described heretofore in which fresh culture medium can be added and spent medium can be separated from the growing cells by filtration and withdrawn from the flask on a continuous or semicontinuous basis as seen from U.S. Pat. Nos. 4,166,768 and 4,178,209.
While ordinary suspension cultures are suitable for growth of certain mammalian cell lines, other cells, and particularly human diploid cells, require support surface means for cell attachment. Examples of such cell culture systems are the monolayer growth systems in T-flasks, roller bottles, artificial capillary propagators and multi-plate propagators. In order to provide the advantages of large scale suspension culture with provision for cell attachment, microcarrier systems have been developed. The successful use of microcarriers for cell culture was first reported by van Wezel, Nature 216, 64-5 (1967). The method of van Wezel consisted of growing cells as monolayers on the surface of positively charged DEAE-Sephadex.RTM. beads suspended in culture media in a stirred vessel. The stirred vessel used by van Wezel was the Bilthoven microbial culture unit described by van Hemert, Biotech. Bioeng. VI, 381-401 (1964). Further description of that system is described by van Wezel et al., Process Biochem., March 1978, pp. 6-8 and 28, wherein it is stated that as far as cultivation of very sensitive cell types, such as human diploid cell strains is concerned, the system is still not completely satisfactory.
A modification of the van Wezel method is described by Levine et al., Somatic Cell Genetics 3, 149-55 (1977) and U.S. Pat. Nos. 4,036,693 and 4,189,534. This system uses essentially a spinner flask with a magnetically driven stirrer bar.
Although the foregoing suspension cell culture systems have their advantages, they do not provide the desired gentle agitation for certain fragile cell types such as human diploid cells. The present invention provides a suspension cell culture system and apparatus which is directed to overcome that problem and which facilitates a gentle agitation that is useful for sensitive cells as well as fragile microcarriers.